A valve is already known from U.S. Pat. No. 3,457,933, Craft, where a fluid stream is directed into two chambers by a piezo-electrically actuated flexible tongue. However, this valve is not contructed of wafers.
A microvalve is already known from not previously published German Patent Application P 39 19 876, corresponding to U.S. Pat. No. 5,161,774, which is produced as a multi-layer structure. The particular importance of this micro-mechanical valve lies in a type of construction, where the static pressure is compensated, which is essentially realized in three layers. With the microvalve not actuated, the fluid flows into an annular chamber the bottom surface of which is formed by an annular diaphragm and which is closed off at the top by the closing member seated on the valve seat. Because of the pressure-compensated construction of the valve, the pre-stressing force of the diaphragm results in a tight seat of the closing member on the valve seat, so that the connection to the outlet connector is blocked. A closed-off cavity, in which a defined pressure is present and to the bottom surface of which an electrode has been applied, is located underneath the annular diaphragm. This electrode is used for electrostatic opening of the valve. To close the valve, the electrostatic drive is shut off, whereupon the closing member again rests on the valve seat because of the effect of the restoring force of the annular membrane The mode of operation of this microvalve requires a complicated structure, where the dimensions of the individual structural elements must be adapted to each other.